Answer:
There are 29 triangles when you count them all including non obvious ones.

Actually Welcome to the concept of expo functions.
f(x) = -8(2)^x - 12 ,
for f(0) ,here substitute x = 0
so we get as ,
==> f(0) = -8(2)^0 -12
==> f(0) = -8-12
==> f(0) = -20
hence, f(0) = -20
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Okay, this is not really an answer, but I think in 2020, we will be in the 20 trillions. O know that is not the answer you were looking for, but its all I got.